Are we programmed to age, or is it just the wear and tear of life?
In short: Professor Lewis Wolpert explores the biological boundaries of growth and ageing in his 1986 Christmas Lectures. From the regenerative powers of hydra to the hormonal triggers that dictate human stature, he investigates how a single fertilized egg transforms into complex life and why our lifespans remain stubbornly fixed.
In his 1986 series 'Frankenstein's Quest', Lewis Wolpert examined the mechanisms behind embryonic development. Every animal originates from a single fertilized egg, which undergoes a complex process of division, movement, and communication to form distinct structures like arms and eyes. This developmental program is highly precise; for instance, human arms grow independently yet reach identical lengths after 18 years. Hormones act as the primary controllers of this growth, with imbalances leading to conditions like gigantism or dwarfism, while sexual differentiation is determined by the Y chromosome triggering testis development.
Regeneration offers a different perspective on biological control. While hydra can regrow a head without new growth, newts require active growth to replace limbs. Wolpert highlights that even simple geometric changes, such as rotating a cockroach leg by 180 degrees, can trigger the growth of extra limbs, suggesting a polar coordinate system governs these developmental patterns. Similarly, evolutionary variations in animal forms, such as the massive antlers of the Irish Elk, may simply result from extending the standard growth period.
Ageing presents a more complex challenge. Wolpert suggests it is a combination of physical wear and tear and the eventual exhaustion of our internal developmental program. Laboratory observations show that normal skin cells possess a finite capacity for division. Despite significant progress in the last century allowing more people to reach old age, the maximum human life-span has not increased. This raises fundamental questions about the nature of mortality: why do different species age at such vastly different rates, and is it scientifically possible to extend life beyond these biological limits?
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Sources
- Summary by Intellect · source: Growing Up & Growing Old - Lewis Wolpert's 1986 Christmas Lectures 6/6
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